1. Field of the Invention
The present invention is directed to a device for aligning sheets, having a sheet acceptance region that is limited by two detents arranged at a right angle relative to one another, and having a sheet positioning mechanism that is arranged within the sheet acceptance region lying opposite the corner limited by the two detents, whereby the sheet positioning mechanism comprises at least one paddlewheel that can be rotationally driven around a drive axis that is approximately parallel to the plane of the sheet acceptance region, so that a sheet supplied to the sheet acceptance region is brought into a seated condition with both detents.
2. Description of the Related Art
European Patent Document EP 0 045 657 A1 discloses a copier device having a mechanism for aligning sheets on a masters"" plate, whereby the sheets are aligned at two detent edges arranged at a right angle. This mechanism comprises two paddlewheels that are arranged in the corner region of the detent walls. The European reference EP 0 045 657 A1 teaches that each paddlewheel is arranged with an angle of 10xc2x0 to 25xc2x0 relative to the neighboring detent edge. As a result thereof, the sheetsxe2x80x94in the region of the paddlewheelsxe2x80x94are moved at high speed by the respective paddlewheels along the neighboring detent edge to the other detent edge.
The axes of the paddlewheels are connected via a flexible shaft that is driven by a motor. Since both paddlewheels are driven by the common flexible shaft, they are synchronized with one another. The paddles of the two paddlewheels are arranged in anti-phase to one another, so that respectively only one paddlewheel has one of its paddles in contact with a sheet. Having two forces directed in different directions act simultaneously on one sheet is thereby avoided.
Sheets are supposed to be aligned faster at the copier device with this known alignment mechanism than would be manually possible.
The above-cited European Patent Document EP 0 045 657 A1 already discloses an alignment device wherein the paddlewheels are arranged with different conveying directions respectively directed to a detent, whereby this document teaches that the conveying direction of each and every paddlewheel should be arranged with an angle of inclination of 10xc2x0 through 25xc2x0 relative to the neighboring detent edge. This means that one of the two paddlewheels has its conveying direction arranged at an angle of 65xc2x0 through 80xc2x0 with respect to the sheet delivery direction. Given high delivery speeds, a supplied sheet is therefore placed into a uncontrolled rotational motion that makes a clean alignment of the sheet at the detents impossible.
U.S. Pat. No. 4,589,654 discloses a deposit compartment for the acceptance and stacking of sheets. This deposit compartment is provided with a mechanism for aligning sheets at two detent walls arranged at a right angle using two paddlewheels. One of the two paddlewheels is arranged in the corner region of the detent walls and is aligned obliquely relative to the two detent walls in order to convey the paper sheets against both detent walls. The other paddle wheel is arranged at the detent wall that is arranged at that side lying opposite the principal conveying direction. This paddlewheel is intended to charge the sheets essentially in the principal conveying direction and with a lower force than the first paddlewheel.
Deposit compartments having such a mechanism for aligning sheets can stack sheets with a rate of up to approximately 8 sheets/minute. This stacking rate can be fundamentally influenced by the following parameters:
Sheet delivery speed with which the sheets are supplied to the deposit compartment; the sheet delivery speed especially influences the flight behavior of the sheets after leaving the last conveyor drums. The sheet delivery speed is usually not varied in a specific device; the sheet delivery speeds of different machines, however, can differ.
Spacing with which the sheets are supplied to the deposit compartment, whereby the sheet rate given a constant sheet delivery speed is all the higher the shorter the spacing between two successive sheets is.
Paper type; the paper type is particularly defined by the format, by the basis weight and the surface.
It has been shown that not all paper types can be as neatly stacked given high stacking rates, as a result whereof the stacking quality can be significantly deteriorated. The main reason for this is comprised in the short time available for stacking.
When the stacking rate is to be increased even further beyond the values of 80 sheets/min, then the known mechanisms for aligning sheets are not in the position of neatly stacking different paper types given the desired stacking rate.
U.S. Pat. No. 5,601,283 discloses a device wherein a angle of a sheet positioning mechanism can be modified relative to a conveying direction, being modified with an adjustment mechanism of the sheets to be positioned.
The present invention is based on an object of providing a device for aligning sheets that can align sheets of different paper types supplied with a high rate (for example, xe2x89xa780 sheets/minute) uniformly at two detents, or abutments, arranged at a right angle.
This and other objects are achieved by a device having a device for aligning sheets having a sheet acceptance region that is limited by two detents, or abutments, arranged at a right angle relative to one another, and a sheet positioning mechanism that is arranged within the sheet acceptance region lying opposite the corner limited by the two detents, whereby the sheet positioning mechanism comprises at least one paddlewheel that can be rotationally driven around a drive axis that is approximately parallel to the plane of the sheet acceptance region, so that a sheet supplied to the sheet acceptance region is brought into a seated condition with both detents, whereby the paddlewheel is a double paddlewheel having two individual paddlewheels arranged side-by-side on the drive shaft, and whereby the individual paddlewheels respectively comprise a base member with paddles applied thereto, and the two individual paddlewheels are seated on the drive shaft with play, so that the paddlewheels can turn by an angle relative to one another on the drive shaft.
In a preferred development, the angle lies in the range from xc2x12xc2x0 through xc2x110xc2x0 and/or in that the two individual paddlewheels are respectively provided with a hole at their base members that is penetrated by a dog pin with play in rotational direction. The sheet positioning mechanism may be adjustable around an axis residing perpendicular to the plane of the acceptance region, so that the conveying direction of the paddlewheel is variable. The axis for the adjustment of the sheet positioning mechanism is a rotational axis proceeding through the center of the paddlewheel, and the drive shaft is seated at an end region of a vertical leg of an L-shaped suspension, whereby the other horizontal leg is arranged above the paddlewheel parallel to the drive shaft. The horizontal leg of the L-shaped suspension is seated at the end region of a paddle lever, being seated rotatable around the rotational axis, whereby the paddle lever has its other end region secured to a mount. Specifically, a driven gear rotatably seated around the rotational axis is provided at the horizontal leg, the rotatory motion thereof being transmitted onto the paddlewheel with a mitre gearing. The driven gear arranged at the suspension is driven by a belt wrapping therearound and around a drive wheel arranged at the mount.
Preferrably, an adjustment mechanism is provided for the adjustment of the conveying direction of the paddlewheel, whereby the adjustment mechanism comprises an adjustment lever that is secured in articulated fashion to an end region of the horizontal leg of the suspension and that is secured to the mount with an adjustment device. The adjustment device is a rotatory lever driven by a stepping motor.
In one embodiment, the axis for the adjustment of the sheet positioning device is a swivelling axis offset from the center of the paddlewheel in the direction to the admission side of the sheet acceptance region, whereby the sheet positioning device can be freely swivelled around the swivelling axis. A damping mechanism may be provided for damping the swivel motion of the paddlewheel. The sheet positioning device is arranged at an end region of a paddle lever and the other end region of the paddle lever is secured to a mount, whereby a drag link is provided at that end region of the paddle lever arranged at the mount, so that at least one part of the paddle lever is fashioned pivotable around the swivelling axis.
The invention also provides a device for aligning paper sheets or the like having a sheet acceptance region that is limited by two detents arranged at a right angle relative to one another, and a sheet positioning mechanism that is arranged within the sheet acceptance region lying opposite the corner limited by the two detents, whereby the sheet positioning mechanism comprises two paddlewheels that can be respectively rotatably driven around a drive axis that is essentially parallel to the plane of the sheet acceptance region and that are arranged with different conveying directions respectively pointing to a detent, so that a sheet supplied to the sheet acceptance region is brought into a seated condition with both detents, the paddlewheels being arranged such that their conveying directions describe an angle with the two detents that lies in the range from 30xc2x0 through 60xc2x0.
The two paddlewheels are arranged on a common, articulated or flexible drive shaft so that they are driven synchronized. The articulated shaft may be a universal joint or an accordion bellows coupling. The paddlewheels can be respectively fashioned of a cylindrical base member having a plurality of radially salient paddles that are arranged at the circumference of the base member with identical spacing from one another, whereby the paddles of the two paddlewheels are arranged offset. The paddlewheels respectively comprise three paddles and the paddles of the two paddlewheels are respectively arranged offset by 60xc2x0 relative to one another. Two paddlewheels can be arranged in such close proximity to one another that the paddles of the two paddlewheels shear into one another. A driven gear is preferably is arranged between the two paddlewheels, the driven gear including a drive shaft stub projecting at both lateral surfaces that are respectively connected in articulated and torsional fashion to a bearing sleeve for the acceptance of respectively one of the paddlewheels. The paddlewheels may be arranged at an end region of a paddle lever, whereby the other end region of the paddle lever is secured to a mount.
The two paddlewheels are preferably adjustable independently of one another around a rotational axis perpendicular to the plane of the acceptance region. Alternatively, the two paddlewheels are respectively provided with a separate suspension that is respectively rotatably hinged to a paddle lever, and a respective adjustment mechanism is provided for the adjustment of the conveying direction of the paddlewheels, whereby the adjustment mechanisms respectively includes an adjustment lever extending approximately parallel to the paddle lever, said adjustment levers being respectively secured articulated to the suspension and, using an adjustment device exerting a rotational motion onto the respective suspension and the corresponding paddlewheel. The conveying directions of the two paddlewheels of one embodiment describe a constant angle and the two paddlewheels are seated at an end region of a paddle lever, whereby the axis for the adjustment of the sheet positioning device is a swivelling axis offset from the common drive shaft in the direction toward the admission side of the sheet acceptance region, whereby the sheet acceptance device is freely pivotable around the swivelling axis. Specifically, the angle between the conveying directions of the two paddlewheels lies in the range from 10xc2x0 through 20xc2x0. A flexible or articulated telescoping rod that compensates the rotational or, respectively, swivel motions is provided for driving the two paddlewheels. The telescoping rod can extend approximately parallel to the paddle lever from a mount to which a paddle lever that holds the paddlewheels is attached up to a mitre gearing connected to the drive shaft of the two paddlewheels.
In a further development, the device for aligning sheets has a sheet acceptance region that is limited by two detents arranged at a right angle relative to one another, and a sheet positioning mechanism that is arranged within the sheet acceptance region lying opposite the corner limited by the two detents, whereby the sheet positioning mechanism comprises at least one paddlewheel that can be rotationally driven around a drive axis that is approximately parallel to the plane of the sheet acceptance region, so that a sheet supplied to the sheet acceptance region is brought into a seated condition with both detents, whereby the sheet positioning device is adjustable around an axis residing perpendicular to the plane of the acceptance region, so that the conveying direction of the paddlewheel is variable.
The invention is based on the perception that the sheets usually do not simultaneously reach the two detents given the known devices for aligning sheets at two detents arranged at a right angle to the transport path. The sheets are quickly driven against one of the two detents and are then moved noticeably more slowly along this detent toward the other detent.
Investigations in the part of the inventor have shown that the detent that the sheets reach first is dependent on the sheet delivery speed and on the sheet type. Due to their high kinetic energy, papers having a high basis weight reach the front detent lying in a sheet delivery direction first, and sheets having a low basis weight reach the detent arranged at the side with respect to the sheet delivery direction first. Short recording media formats with respect to the sheet running direction reach the lateral detent first, in contrast whereto longer formats reach the front detent first. The effects due to the basis weight and the format superimpose on one another.
In a first aspect of the invention, these problems are eliminated in that the paddlewheel is a double paddlewheel having two individual paddlewheels arranged side-by-side on the drive shaft, whereby the individual paddlewheels respectively comprise a base member with paddles applied thereto, and the two individual paddlewheels are seated on the drive shaft with play, so that the paddlewheels can turn by an angle relative to one another on the drive shaft.
In a second aspect of the invention, which can also solve the aforementioned problem independently of the first aspect, it is provided that a sheet positioning mechanism is adjustable around an axis residing perpendicularly to the plane of the acceptance region, so that the conveying direction of the paddlewheel is variable.
According to this second aspect, the conveying direction of the paddlewheel can be set dependent on the paper type such that the sheets reach the two detents essentially simultaneously. Fundamentally, an adaptation to the modification of the sheet delivery speed is also possible. As a result thereof, the slow conveying speed along one of the two detents is avoided, and a considerable time-saving is achieved in the alignment of the sheets.
According to a third aspect of the invention, which can likewise achieve the object independently of the two aspects cited first, two paddlewheels directed in different directions respectively pointing to a detent are provided, whereby their conveying directions describe an angle with the two detents that lies in the range is from 30xc2x0 through 60xc2x0 and, preferably, in the range from 35xc2x0 through 55xc2x0.
It has been shown that the supplied sheets are quickly delivered to the one detent by one of the two paddlewheels and are quickly delivered to the other detent by the other paddlewheel. When the conveying directions are not variable, it can in fact not be assured that the two detents are reached simultaneously, as in the first solution set forth above; however, the gradual conveying event along one of the two detents given the known alignment devices is considerably shortened since the sheets are simultaneously conveyed to the two detents in the invention, as a result whereof a clear saving of time is achieved in the alignment of the sheets.
A preferred embodiment of the invention, particularly of the aforementioned second aspect, has the shaft for the adjustment of the sheet positioning mechanism as a swivelling shaft offset from the center of the paddlewheel in the direction toward the admission side of the sheet acceptance region, whereby the sheet positioning mechanism can be freely swivelled around the shaft.
Given this alignment device, the optimum angle of the conveying direction of the paddlewheel is automatically set, since an increased resistance directed opposite the detent opposes the paddlewheel when this detent is reached, the paddlewheel evading this resistance in the direction to the other detent. When the sheet simultaneously reaches both detents, a force equilibrium occurs at the paddlewheel, so that the paddlewheel is no longer swivelled around the swivelling shaft, whereby the conveying direction is set such that the sheet to be aligned simultaneously reaches both detents. Employing the simplest technical outlay, an arrangement that automatically adjusts to the optimum angle is created, so that the incoming sheets simultaneously reach the two detents.
This embodiment with self-adjusting conveying direction of the paddlewheel can also be fashioned with a double paddlewheel.